Prepare corn tortilla recipe according to instructions. Cover with plastic wrap and set aside until ready to use.
For salsa, transfer all of the ingredients to a pot. Cover with water. Heat to medium, bring up to a light boil and cook just until tomatillos turn color (about 10 minutes). Remove from heat. Once cooled, drain water then transfer ingredients to the blender. Season with salt, to taste, and blend on high until smooth. Set aside.
Heat 2 tablespoons of grapeseed oil at medium in a large skillet. Add the onions and jalapenos. Sautee for 5 minutes. Add the garlic and saute for one more minute. Mix in the chicken and 3/4 of the reserved salsa verde. Mix well. Taste for salt. Continue cooking at a steady simmer until salsa reduces and thickens.
To prepare puffy shells, at medium heat, preheat 4 cups of oil in sauce pan for 6-7 minutes.
Line a tortilla press with plastic cut out from a plastic storage bag. Press masa ball gently until you have a tortilla that is about 4 1/2-5 inches wide.
Carefully peel plastic away from pressed tortilla. Holding the uncooked tortilla with two hands, carefully drop it into hot oil. When the tortilla floats to the top, carefully spoon some hot oil over the top of tortilla. When it puffs up, flip it over. Count 5 seconds and then gently take a metal or wooden spoon and press into center of inflated(puffed) tortilla. Push it towards edge of pot and hold it there for 1 minute. Drain the shells on wire rack lined with baking sheet.
If you like, you can transfer the shells to a low temperature oven to keep them warm and crisp. When ready, fill puffy taco shells with warm chicken in salsa. Garnish with extra salsa, sour cream, cheese, lettuce, tomato, avocado and onion. Chicken filling yields up to 24 tacos.